Chemical and pharmaceutical industries, and chemical-related government agencies, such as the National Cancer Institute (NCI) commonly maintain large chemical substance databases and provide structure searching capabilities in association with such databases. Recently, these organizations have been standardizing on relational database management systems (RDBMS), such as the ORACLE RDBMS. The advantages of integrating chemical structure information with an RDBMS include: A closer integration with other related chemical data, efficiency of the RDBMS in storage and retrieval of data, and better access to the chemical structure data by other related applications. This Phase II research is directed at developing a complete chemical information system, the core of which is a chemical structure search system based on relational database technology. This work will provide direct benefit to NCI in terms of porting the chemical structure handling capabilities from the present hierarchically- organized Drug Information System (DIS) to the ORACLE RDBMS.